New York, April 03, SPA --UN Secretary General Ban Ki-moon said todaythat US-Russian leadership is vital to implement treaties banning theproliferation of nuclear weapons, according to dpa. US President Barack Obama and his Russian counterpart DmitriMedvedev agreed during their meeting in London Wednesday to committo draw up a new deal on nuclear disarmament to replace the US-Russian strategic weapons reduction programme (START) which expiresat the end of 2009. "The secretary general believes that their leadership is vital tothe process leading to the achievement of a nuclear-free world," saida statement from Ban. Ban also welcomed Obama's statement that the US would ratify theComprehensive Nuclear Test Ban Treaty (CTBT) dealing with nuclearballistic missiles.--SPA www.spa.gov.sa/650767